Facile Co-precipitation Method Research Articles

Facile synthesis of visible-responsive photocatalytic Eu-doped layered double hydroxide for selective removal of NOx pollutant

Efficient nitrogen oxides (NOx) removal from the urban atmosphere is still a target for the researchers. Herein, a Zn2Al-CO3 based layered double hydroxide (LDH) was doped with increasing amounts of Eu3+ (0.01–0.04) and the photocatalytic oxidation of NOx gases was investigated. The LDHs were synthesized by a facile coprecipitation method at room temperature and ambient pressure. The successful Eu3+ substitution in the LDH layers induces a shift in the M−O bonds that modifies the electronic band structure of the doped photocatalysts. Compared to the undoped LDH, the NOx removal efficiency was enhanced by ∼ 17–25 % under UV–Vis light irradiation. Remarkably, a NOx removal efficiency of ∼ 47 % was attained by the optimally doped LDH under Visible irradiation (420 nm), surpassing raw LDH (∼ 9 %). Moreover, the Eu3+ doped LDHs retained its photocatalytic efficiency during long periods of irradiation during consecutive tests with high selectivity (>90 %). Photoluminescence studies indicated that Eu3+ was located in a non-centrosymmetric position, thereby producing structural disorder within the lattice. Eu doping promoted charge separation and a higher production of ⋅OH radicals as verified by time-resolved photoluminescence and electron paramagnetic resonance, respectively. We believe this work reports unprecedent results obtained by Eu-doping of Zn2Al-based LDHs under visible light for NOx photooxidation and serves as a new strategy to prepare functional LDHs for other photocatalytic applications.

Endogenous Fe2+-activated nanomedicine to amplify ROS generation and in-situ response NIR-II photothermal therapy of tumor

Endogenous activated nanomedicines have great potential in improving therapeutic efficacy and minimizing side effects in cancer therapy. Herein, a novel nanomedicine (CuHCF) was developed based on a mixed-metal (Cu2+/Fe3+) Prussian blue analogue via a facile co-precipitation method, which could respond to the endogenous labile iron pool (LIP) achieving enhanced chemodynamic therapy (CDT) and in situ NIR-II photothermal therapy (PTT) of tumor. Notably, the prepared CuHCF itself shows low Fenton catalytic activity, which however, is found to significantly amplify the generation of reactive oxidative species (ROS) when exposed to the over-expressed Fe2+ in tumor region, since the intracellular Fe2+ triggers the redox cycles between Fe3+/Fe2+ and Cu2+/Cu+ of CuHCF. More interestingly, it is found that the CuHCF presents an obviously enhanced near-infrared absorption after reacting with Fe2+, enabling in situ hyperthermia under NIR-II (1064 nm) irradiation. Both in vitro and in vivo results demonstrated that a highly efficient synergistic therapy of CDT/PTT was achieved via a ferroptosis pathway when CuHCF was combined with the ferroptosis inducer erastin (ERA). Such an endogenous activated nanomedicine provides a promising paradigm to enhance specific CDT in synergy with in situ NIR-II PTT for precise cancer therapy.

Ni-doped Mg-Zn nano-ferrites: Fabrication, characterization, and visible-light-driven photocatalytic degradation of model textile dyes

Novel Ni2+-doped NixMg0.5Zn0.5-xFe2O4 [x = 0.0 to 0.5] nano-ferrites have been successfully prepared by the facile co-precipitation method. The XRD data demonstrated the formation of a single-phase cubic spinel structure. The optical band gap of the synthesized samples was found to increase with increasing Ni2+ content from 1.72 eV (x = 0.1) to 1.82 eV (x = 0.5). Samples with Ni2+ doping exhibit a transition from superparamagnetic to soft ferromagnetic activity. Ni0.5Mg0.5Fe2O4 catalyst has been found to have enhanced degrading efficiencies of 95.92 and 90.21% against methylene blue and xylenol orange in visible light, respectively. The main reactive species, as determined by scavenging activity, were hydroxyl radicals.

Tuning the intrinsic catalytic sites of magnetite to concurrently enhance the reduction of H2O2 and O2: Mechanism analysis and application potential evaluation

Heterogeneous Fenton-like process based on H2O2 activation has been widely tested for water purification, but its application still faces some challenges such as the use of high doses of chemicals (including catalysts and H2O2). Herein, a facile co-precipitation method was utilized for small-scale production (∼50 g) of oxygen vacancies (OVs)-containing Fe3O4 (Vo-Fe3O4) for H2O2 activation. Experimental and theoretical results collaboratively verified that H2O2 adsorbed on the Fe site of Fe3O4 tended to lose electrons and generate O2•-. While the localized electron from OVs of Vo-Fe3O4 could assist in donating electrons to H2O2 adsorbed on OVs sites, this allowed more H2O2 to be activated to •OH, which was 3.5 folds higher than Fe3O4/H2O2 system. Moreover, the OVs sites promoted dissolved oxygen activation and decreased the quenching of O2•- by Fe(III), thus promoting the generation of 1O2. Consequently, the fabricated Vo-Fe3O4 achieved much higher oxytetracycline (OTC) degradation rate (91.6%) than Fe3O4 (35.4%) at a low catalyst (50 mg/L) and H2O2 dosage (2 mmol/L). Importantly, further integration of Vo-Fe3O4 into fixed-bed Fenton-like reactor could effectively eliminate OTC (>80%) and chemical oxygen demand (COD) (21.3%∼50%) within the running period. This study provides promising strategies for enhancing the H2O2 utilization of Fe mineral.

Spinel cobalt ferrite-based porous activated carbon in conjunction with UV light irradiation for boosting peroxymonosulfate oxidation of bisphenol A

Developing heterogeneous catalysts with high performance for peroxymonosulfate (PMS) activation to decontaminate organic pollutants from wastewater is of prominent importance. In this study, spinel cobalt ferrite (CoFe2O4) materials were coated on the surface of powdered activated carbon (CoFe2O4@PAC) via the facile co-precipitation method. The high specific surface area of PAC was beneficial for the adsorption of both bisphenol A (BP-A) and PMS molecules. The CoFe2O4@PAC-mediated PMS activation process under UV light could effectively eliminate 99.4% of the BP-A within 60 min of reaction. A significant synergy effect was attained between CoFe2O4 and PAC towards PMS activation and subsequent elimination of BP-A. Comparative tests demonstrated that the heterogeneous CoFe2O4@PAC catalyst had a better degradation performance in comparison with its components and homogeneous catalysts (Fe, Co, and, Fe + Co ions). The formed by-products and intermediates during BP-A decontamination were evaluated using LC/MS analysis, and then a possible degradation pathway was proposed. Moreover, the prepared catalyst exhibited excellent performance in recyclability with slight leaching amounts of Co and Fe ions. A TOC conversion of 38% was obtained after five consecutive reaction cycles. It can be concluded that the PMS photo-activation process via the CoFe2O4@PAC catalyst can be utilized as an effective and promising method for the degradation of organic contaminants from polluted-water resources.

Highly foldable and free-standing supercapacitor based on hierarchical and hollow MOF-anchored cellulose acetate carbon nanofibers

Flexible electrode materials have achieved great breakthroughs during the past decades. However, many challenges remain such as how to overcome the frangibility and enhance the flexibility, and advance the high specific capacitance. We fabricated a free-standing, foldable, and conductive cellulose acetate (CA)-based metal-organic framework (MOF) composites by facile electrospinning carbonization and co-precipitation method. The sustainable cellulose derivative provides a flexible matrix, which contains hierarchically porous and ample redox activities. The intermolecular interaction is enhanced for coordination between exposed hydroxyl on deacetylated CA and metal ions, thus reduce the fracture of the CA nanofibers. Importantly, multi-layer heterojunction structure and honeycomb-like MOF nanosheets with reversibly flexible deformation create interlamellar pathways to improve the bending resistance of nanofibers. The controlled Co/Zn ion concentration could effectively modulate spatial distribution of Co/Zn MOF to thus generate different conductive channels. The asymmetric flexible supercapacitor based on Ni/Co LDH@ Co/Zn NC@CDCP-N electrode material gives high specific capacitance (175.2 F g−1 at 1 A g−1) and outstanding energy density (54.8 W h kg−1) at high power density (985.5W kg−1). Our work paves a way to facile fabrication of flexible and free-standing electrode materials for practical flexible energy storage, such as artificial electronic skin and soft wearable electronics.

Synergistic contribution of metal–acid sites in selective hydrodeoxygenation of biomass derivatives over Cu/CoOx catalysts

The efficient hydrodeoxygenation (HDO) of biomass derivatives to yield specific products is a significant yet challenging task. In the present study, a Cu/CoOx catalyst was synthesized using a facile co-precipitation method, and subsequently used for the HDO of biomass derivatives. Under optimal reaction conditions, the conversion of 5-hydroxymethylfurfural reached 100% with a selectivity of ∼99% to 2,5-diformylfuran. In combination with the experimental results, systematic characterizations revealed that CoOx, as the acid site, tended to adsorb CO bonds, and the metal sites of Cu+ were inclined to adsorb CO bonds and enhance CO bond hydrogenation. Meanwhile, Cu0 was the main active site for 2-propanol dehydrogenation. The excellent catalytic performance could be attributed to the synergistic effects of Cu and CoOx. Further, by optimizing the ratio of Cu to CoOx, the Cu/CoOx catalysts exhibited notable performance in HDO of acetophenone, levulinic acid, and furfural, which verified the universality of the catalysts in the HDO of biomass derivatives.

Low-temperature synthesis, characterization and photocatalytic properties of lanthanum vanadate LaVO4

In this study, we have successfully prepared tetragonal lanthanum vanadate LaVO4 nanoparticles by a facile co-precipitation method at room temperature. The obtained materials were characterized using different structural and micro-structural techniques such as the characterization by X-ray diffraction (XRD), UV–Vis diffuse reflectance spectrum (DRS), transmission electron microscopy (TEM), and Raman spectrometry. The obtained structure is crystallized in single tetragonal phase with pin-like nanostructure. A main optical transition with bandgap energy of 3.26 eV is evidenced, and the average lifetime of charges carriers was found to be 1 ns Furthermore, the photoluminescence occurs in the visible light range. The photocatalytic activity was evaluated by the photocatalytic degradation of methylene blue (MB) with initial concentration of 10 mg L−1. The result indicates that LaVO4 particles showed a best photocatalytic activity of 98.2% degradation for methylene blue solution after irradiation of 90 min under visible light. Furthermore, the photocatalytic mechanism and reusability were studied.

Spongy magnetic hydroxyapatite for the enhanced Pb2+ removal and its dynamic sorption mechanism

Nano-magnetic hydroxyapatite (Fe3O4/nHAP) has superior properties for the removal of lead (Pb) from aqueous solutions. In this study, we synthesized several spongy Fe3O4/nHAP composite materials using the facile chemical co-precipitation method with the assist of ultrasound. Appropriate Fe3O4 addition increased the specific surface area of Fe3O4/nHAP with a porous structure, contributing to the more sorption sites exposure to lead ions (Pb2+) for fast kinetic and larger sorption capacity of 1500 mg g-1. The characteristic results manifest that complexation and dissolution-precipitation were the two main sorption mechanisms. Through the Pb/Ca molar ratio, solution pH, Pb fraction changes and the additional XRD results, the main sorption mechanisms turned from complexation to dissolution-precipitation and the adsorbed-Pb transformed from unstable Pb-complexes to stable Pb-phosphate during the removal process. Complexation effect dominated the Pb2+ removal in higher Pb2+ concentration solutions while dissolution-precipitation controlled in low Pb2+ concentration solutions. Pb5(PO4)3(OH) was the main product in the solutions of pH ranging from 2.76 to 5.25, and PbHPO4 precipitates was formed when the pH was lower than 2.76. Regeneration experiment and fraction analysis demonstrated the stability of Fe3O4/nHAP after Pb2+ sorption and desorption. Our findings provide a facile preparation method of Fe3O4/nHAP with their specific properties for the Pb2+ removal from aqueous solutions. Comprehensive mechanisms for the affinity of Pb2+ and Fe3O4/nHAP can propose strategies in the further removal or stabilization of heavy metals in practical environmental remediation.

Phosphorous recovery from water via batch adsorption enrichment combined with struvite crystallization in a fluidized bed reactor

To assess the feasibility of recovering P from water by combining batch adsorption enrichment with struvite crystallization, we prepared four ternary layered double hydroxides (LDHs) with P-preferring elements (i.e., zirconium (Zr) or lanthanum (La)) via a facile coprecipitation method, and evaluated their performance in recovering P from water, particularly in enriching P from a low-level P solution. We find that all ternary LDHs demonstrate remarkably high P adsorption capacities, e.g., 1029.3 mg PO43− g−1 for ZnAlLa, outperforming other LDHs reported so far. Microstructural analyses show that the P uptake mechanisms are attributable to anion exchange, surface complexation and electrostatic attraction. Results of recycling tests indicate that all LDHs present good enrichment for P. Besides, more than 96% of phosphorus in the P-enriched eluates can be efficiently reclaimed via struvite crystallization in a fluidized bed reactor. These findings demonstrate the feasibility of combining adsorption enrichment with struvite crystallization for P recovery.

Boosting the performance of Co-doped CeO2 catalyst in the catalytic oxidation of toluene by modulating oxygen vacancies

Metal doping is one of the most effective strategies to enhance redox capacity and modulate the oxygen vacancies in Ce-based catalysts. This manuscript reports a Co-doped CeO2 catalyst (Co0.2Ce0.8 (W/E = 1/1)) for the catalytic oxidation of toluene fabricated by a facile co-precipitation method. The appropriate ratio of deionized (DI) water/ethanol in the reaction solvent contributed to the mesocrystallization of the CeO2 phase and the highly uniform dispersion of the Co-O-Ce mixed bond in the catalyst. The feasible lattice distortion induced the generation of richer oxygen vacancies in both the surface and bulk of the catalyst. Meanwhile, the efficient cycle of Co2+ + Ce4+ ↔ Co3+ + Ce3+ enhanced the redox property of the catalyst. As revealed by in situ DRIFTS studies, the as-formed surface oxygen vacancies promoted the adsorption and partial oxidation of toluene. The oxygen vacancies in the bulk of the catalyst improved the migration of lattice oxygen, accelerating the mineralization of the aromatic ring. Thus, the excellent low-temperature oxidation of toluene by Co0.2Ce0.8 (W/E = 1/1), reducing T90 to 192 °C, was attributed to the synergism between the catalyst’s surface and bulk oxygen vacancies.

CeO2 quantum dots decorated g-C3N4 nanosheets: A potential scaffold for fluorescence sensing of heavy metals and visible-light driven photocatalyst

Herein, we report the synthesis of g-C3N4/CeO2 heterostructure using a facile co-precipitation method. The as-synthesized g-C3N4/CeO2 heterostructure was examined by several techniques in order to understand the morphology, thermal, structural, optical and compositional properties. A strong interfacial contact was observed between g-C3N4 nanosheets and CeO2 quantum dots (QDs) as CeO2 QDs were deposited on g-C3N4 nanosheets with slight agglomeration. The as-synthesized heterostructure was successfully applied as a probe for the fluorescence sensing of heavy transition metals (Cu(II), Hg(II) and Ag(I)) and a visible light active photocatalyst for the decomposition of tetracycline (TC) in an aqueous phase. The g-C3N4/CeO2 heterostructure exhibited remarkable selectivity towards the sensing of Cu(II), Hg(II) and Ag(I) heavy metal ions because of strong binding affinity of these metal ions towards nitrogen and oxygen containing functional moieties present in g-C3N4/CeO2 heterostructure. Furthermore, a good linearity was observed between the relative FL intensity and concentration of Cu(II), Hg(II) and Ag(I) ions with detection limit estimated to be 26.2 µM, 17.5 µM and 14.9 µM, respectively. The high selectivity for these ions was due to their strong binding affinity towards nitrogen and oxygen containing functional groups in g-C3N4/CeO2 heterostructure. Moreover, the removal efficiency of 77.95% was acquired for degradation of tetracycline in 160 min using g-C3N4/CeO2 heterostructure under optimized conditions. The photocatalytic results of the heterostructure could be accredited to the reduction in the recombination of excited carriers across the interface of the heterojunction. Therefore, the present work provides an effective strategy for the preparation of fluorescent photocatalytic materials that can be utilized for the FL detection of harmful heavy metal ions as well as degradation of pollutants in an aqueous phase.

Co/Fe3O4@GO catalyst for one-step hydrogen generation from hydrolysis of NaBH4: Optimization and kinetic study

In this study, cobalt nanocatalysts supported on the Fe3O4@GO were synthesized for boosting hydrogen generation upon hydrolysis of sodium borohydride. Co/Fe3O4@GO catalysts were synthesized through a facile co-precipitation method followed by a chemical reduction step. The prepared samples were characterized using various techniques including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Vibrating sample magnetometer (VSM), and Nitrogen adsorption–desorption (BET). Benefiting from the high crystallinity, good dispersion of Co nanoparticles over the Fe3O4@GO, and the synergistic effect between Co nanoparticles and Fe3O4@GO support, Co/Fe3O4@GO catalysts with 30 wt% cobalt loading showed the highest catalytic activity with high hydrogen generation rate of 4000 mL/min.gcat and relatively good stability. To investigate the effect of the parameters on hydrogen generation rate and optimal reaction conditions, the Box-Behnken design under response surface methodology (RSM) was applied. ANOVA results denoted that the temperature with the highest F-value and lowest P-value had the most effect on the hydrogen generation rate. Under the optimum conditions including a temperature of 39.83 °C, 17.74 mg of catalyst, and 5.135 wt% NaBH4 concentration, Co(30%)/Fe3O4@GO exhibited a superior H2 generation rate of 6005 mL/min.gcat and low activation energy of 44.4 kJ/mol. Therefore, the Co/Fe3O4@GO is a promising catalyst for NaBH4 hydrolysis due to its easy preparation and separation method, high hydrogen generation rate, and low activation energy.

Synergetic Photocatalytic Peroxymonosulfate Oxidation of Benzotriazole by Copper Ferrite Spinel: Factors and Mechanism Analysis.

The development of oxidation processes with the efficient generation of powerful radicals is the most interesting and thought-provoking dimension of peroxymonosulfate (PMS) activation. This study reports the successful preparation of a magnetic spinel of CuFe2O4 using a facile, non-toxic, and cost-efficient co-precipitation method. The prepared material exhibited a synergetic effect with photocatalytic PMS oxidation, which was effective in degrading the recalcitrant benzotriazole (BTA). Moreover, central composite design (CCD) analysis confirmed that the highest BTA degradation rate reached 81.4% after 70 min of irradiation time under the optimum operating conditions of CuFe2O4 = 0.4 g L-1, PMS = 2 mM, and BTA = 20 mg L-1. Furthermore, the active species capture experiments conducted in this study revealed the influence of various species, including •OH, SO4•-, O2•-, and h+ in the CuFe2O4/UV/PMS system. The results showed that SO4•- played a predominant role in BTA photodegradation. The combination of photocatalysis and PMS activation enhanced the consumption of metal ions in the redox cycle reactions, thus minimizing metal ion leaching. Additionally, this maintained the reusability of the catalyst with reasonable mineralization efficiency, which reached more than 40% total organic carbon removal after four batch experiments. The presence of common inorganic anions was found to have a retardant effect on BTA oxidation, with the order of retardation following: HCO3- > Cl- > NO3- > SO42-. Overall, this work demonstrated a simple and environmentally benign strategy to exploit the synergy between the photocatalytic activity of CuFe2O4 and PMS activation for the treatment of wastewater contaminated with widely used industrial chemicals such as BTA.

Efficient Near-Infrared Luminescence Based on Double Perovskite Cs2SnCl6.

Cs2SnCl6 double perovskite has attracted wide attention as a promising optoelectronic material because of its better stability and lower toxicity than its lead counterparts. However, pure Cs2SnCl6 demonstrates quite poor optical properties, which usually calls for active element doping to realize efficient luminescence. Herein, a facile co-precipitation method was used to synthesize Te4+ and Er3+-co-doped Cs2SnCl6 microcrystals. The prepared microcrystals were polyhedral, with a size distribution around 1-3 μm. Highly efficient NIR emissions at 1540 nm and 1562 nm due to Er3+ were achieved in doped Cs2SnCl6 compounds for the first time. Moreover, the visible luminescence lifetimes of Te4+/Er3+-co-doped Cs2SnCl6 decreased with the increase in the Er3+ concentration due to the increasing energy transfer efficiency. The strong and multi-wavelength NIR luminescence of Te4+/Er3+-co-doped Cs2SnCl6 originates from the 4f→4f transition of Er3+, which was sensitized by the spin-orbital allowed 1S0→3P1 transition of Te4+ through a self-trapped exciton (STE) state. The findings suggest that ns2-metal and lanthanide ion co-doping is a promising method to extend the emission range of Cs2SnCl6 materials to the NIR region.

High specific surface area γ-Al2O3 nanoparticles synthesized by facile and low-cost co-precipitation method

Alumina (Al2O3) nanoparticles (NPs) are particularly adsorbent NPs with a high specific surface area (SSA) that may well be utilized to clean water. In this study, pure γ-alumina NPs are successfully synthesized by the co-precipitation method, and the effect of ammonium bicarbonate concentration on the synthesized NPs is studied to find the optimum concentration to provide the highest capacity of copper ions removal from water. The results declare that spherical alumina NPs with average diameters in the range of 19–23 nm are formed with different concentrations of precipitation agent, and the concentration has no significant effect on the morphology of NPs. Furthermore, the precipitating agent concentration influences the optical characteristics of the produced alumina NPs, and the bandgap energies of the samples vary between 4.24 and 5.05 eV. The most important impact of precipitating agent concentrations reflects in their SSA and capacity for copper ion removal Ultra-high SSA = 317 m2/g, and the highest copper removal at the adsorbate concentration of 184 mg/L is achieved in an alkalis solution followed by a neutral solution. However, admirable copper removal of 98.2% is even achieved in acidic solutions with 0.9 g/L of the alumina NPs synthesized at a given concentration of ammonium bicarbonate, so this sample can be a good candidate for Cu ions removal from acidic wastewater.

Outstanding Electrochemical Performance of Ni-Rich Concentration-Gradient Cathode Material LiNi0.9Co0.083Mn0.017O2 for Lithium-Ion Batteries.

The full-concentrationgradient LiNi0.9Co0.083Mn0.017O2 (CG-LNCM), consisting of core Ni-rich LiNi0.93Co0.07O2, transition zone LiNi1-x-yCoxMnyO2, and outmost shell LiNi1/3Co1/3Mn1/3O2 was prepared by a facile co-precipitation method and high-temperature calcination. CG-LNCM was then investigated with an X-ray diffractometer, ascanning electron microscope, a transmission electron microscope, and electrochemical measurements. The results demonstrate that CG-LNCM has a lower cation mixing of Li+ and Ni2+ and larger Li+ diffusion coefficients than concentration-constant LiNi0.9Co0.083Mn0.017O2 (CC-LNCM). CG-LNCM presents a higher capacity and a better rate of capability and cyclability than CC-LNCM. CG-LNCM and CC-LNCM show initial discharge capacities of 221.2 and 212.5 mAh g-1 at 0.2C (40 mA g-1) with corresponding residual discharge capacities of 177.3 and 156.1 mAh g-1 after 80 cycles, respectively. Even at high current rates of 2C and 5C, CG-LNCM exhibits high discharge capacities of 165.1 and 149.1 mAh g-1 after 100 cycles, respectively, while the residual discharge capacities of CC-LNCM are as low as 148.8 and 117.9 mAh g-1 at 2C and 5C after 100 cycles, respectively. The significantly improved electrochemical performance of CG-LNCM is attributed to its concentration-gradient microstructure and the composition distribution of concentration-gradient LiNi0.9Co0.083Mn0.017O2. The special concentration-gradient design and the facile synthesis are favorable for massive manufacturing of high-performance Ni-rich ternary cathode materials for lithium-ion batteries.

Excellent Sensitive Temperature Sensing Performance Based on Fluorescence Intensity Ratio Technique of Yb3+/Er3+ Codoped Gd2(WO4)3

For noncontact temperature sensing, the fluorescence intensity ratio (FIR) technique based on thermally coupled levels has great prospects. Within this technique, Yb3+/Er3+ codoped upconversion (UC) particles are regarded as efficient material. Juanqin Xue and co-workers (article number 2200471) have prepared Yb3+/Er3+ codoped Gd2(WO4)3 particles by a facile coprecipitation method and subsequent calcination. The crystal structure, microstructure, and UC emission of the particles are studied in detail, and the optimum temperature sensing performance is systematically measured. Excellent temperature-sensitive properties of Gd2(WO4)3:Yb3+/Er3+ demonstrate great potential for its application in noncontact optical temperature sensors.

Multiferroics Made via Chemical Co-Precipitation That Is Synthesized and Characterized as Bi(1−x)CdxFeO3

Cd-doped BiFeO3 powders, with varying doping concentrations of Cd (Bi(1−x)CdxFeO3, where x = 0–0.3), were prepared through a facile chemical co-precipitation method and calcinated at 550 °C in the air. The BiFeO3 has a rhombohedral crystal structure, which changes to an orthorhombic crystal structure with an increase in Cd doping. The presence of dopant has also altered the bandgap of material suppressing it from 2.95 eV to 2.51 eV, improving the visible light absorption. Vibrating sample magnetometry (VSM) confirmed stronger ferromagnetic character for Bi0.7Cd0.3FeO3 with a coercivity of 250 Oe, and remnant magnetization was 0.15 emu/g, which is because of the misalignment of the two sublattices of perovskite structure after doping resulting in the imbalanced magnetic moment giving rise to net nonzero magnetic behavior. The particle size reduction is observed with an increase in the doping concentration of Cd.

Ultra-Highly Active Ni-Doped MOF-5 Heterogeneous Catalysts for Ethylene Dimerization.

Here, an ultra-highly active Ni-MOF-5 catalyst with high Ni loading for ethylene dimerization is reported. The Ni-MOF-5 catalysts are synthesized by a facile one-pot co-precipitation method at room temperature, where Ni2+ replaces Zn2+ in MOF-5. Unlike Zn2+ with tetrahedral coordination in MOF-5, Ni2+ is coordinated with extra solvent molecules except for four-oxygen from the framework. After removing coordinated solvent molecules, Ni-MOF-5 achieves an ethylene turnover frequency of 352000h-1 , corresponding to 9040g of product per gram of catalyst per hour, at 35°C and 50bar, far exceeding the activities of all reported heterogeneous catalysts. The high Ni loading and full exposure structure account for the excellent catalytic performance. Isotope labeling experiments reveal that the catalytic process follows the Cossee-Arlman mechanism, rationalizing the high activity and selectivity of the catalyst. These results demonstrate that Ni-MOF-5 catalysts are very promising for industrial catalytic ethylene dimerization.